1. Field of the Invention
The present invention relates to an optical packet switching method in which packet-by-packet optical packet switching is enabled by driving an optical switch according to destination information assigned to an optical packet signal.
2. Description of the Related Art
The technology of switching the path depending on the wavelength in an optical transmission system based on wavelength division multiplexing (WDM) and by employing a wavelength selective switch (WSS) is in practical use. One of the next-generation technologies studied is an optical packet switching system in which the path is switched in smaller units, namely, IP packets (10 Gigabit Ethernet (registered trademark) signals, etc.). Each packet is converted in format into an optical packet and routed by using an ultrahigh-speed optical switch (see e.g., patent document No. 1).
When the transmission is based on IP packets, no significant information is transmitted absent any data so that the bandwidth is wasted accordingly. If the optical packet switching system is realized, however, any idle time in which data is absent can be occupied by another packet. Therefore, the optical packet switching system promises the possibility of dramatically increasing the bandwidth usage efficiency of the transmission path and is envisaged as a technology of the future.
[Patent document No. 1] JP 2008-235986
In an optical packet switching device, there are occasions when a plurality of optical packet signals received at the same time by a plurality of input units request output to a same output unit. In such a case, the optical packet switching device performs switching using an optical packet signal received first as a valid optical packet signal and discards the following optical packet.
However, the degree of priority for transmission may be set for a client signal such as, e.g., an Ether signal according to the type of data. In this situation, it is preferred to efficiently transmit a client signal with a high degree of priority.